There are three categories of front-end electronics in the present
CLEO II
detector: digital systems associated with the trigger systems, LeCroy FASTBUS
ADC's for the CsI, and CLEO-specific time-to-voltage and charge-to-voltage
sample/holds (S/H) for the various drift chamber, muon, and time-of-flight
systems. The front-ends are susceptible to three sources of background: cosmic
rays, stray beam particles, and synchrotron radiation. The first one can be
dealt with at the trigger level and the rate is low enough that overlap with
physics events is negligible. This is not necessarily true in the cases of
stray beam particles and
synchrotron radiation, however. For example, due to the CLEO II single hit
electronics, which have a memory time of a couple of microseconds, 10%of the VD cells read for an event appear to be the result of synchrotron
photons and stray beam particles.